(Classic Computers) HP 7970 1/2" 9-Track Reel-to-Reel Tape Drive

Jack Harper harper at secureoutcomes.net
Thu Oct 5 18:37:13 CDT 2017



Chuck -

Great information!

E.g., connectors from Anchor Electronics/San Diego - I have been 
wondering about primordial connectors.

I appreciate the description of your STM32F407 machine - makes sense 
and gives me hope that I can replicate the functionality in the 68K world.

I do have a dual trace 'scope and usually manage to use it without 
hurting myself too badly with a screwdriver or something :)

I have not looked yet - just printed the HP documentation - but are 
the lines into/out of the 7970 tape drive +5VDC etc or something 
weird that I will have to convert.  I "assume" that the current draws 
are reasonable for a GPIO approach?


Regards to the List,

Jack






>If you get a 7970B or -C, get the service+operation manual from the HP
>Museum.  Al has a bunch of 7970 stuff on bitsavers, but not, I think (I
>could be wrong) the manual specific to the B and C models.  All of the
>HP manuals have lots of detail (the drives had almost endless revisions
>and additions, which can be confusing if you're just trying to figure
>out what you've got)--and still, your drive may be slightly different.
>
>For example, I've got a -B made in 1984 and the write-protect mechanism
>doesn't match any of the variations in the manual.  This was important
>to me as on of the microswitches was broken on mine.
>
>But now that I've got the -B outfitted with 7/9 track read stack, write
>protect doesn't matter so much.  I"m still tweaking the various
>adjustments on the drive (have a dual-trace 'scope handy) and it's
>getting very good.
>
>Currently, I'm using it to read old 7-track tapes and create SIMH .TAP
>files on a (shared) SDCard.
>
>I used a generic STM32F407 evaluation board, mounted it on a hunk of
>prototype board and fit a 50 line ribbon connectors to it.  Hookup
>between the MCU board and the connector was done with wire-wrap.  The
>MCU board even has a battery-backed real-time clock on it, so my files
>are all correctly date-stamped.   I got the 48-conductor edge connectors
>for the other end of the cable from Anchor Electronics in San Jose.
>
>For switching between the heads, I built a small board that bolts to the
>head mounting plate and contains a 34-line ribbon connector for the head
>leads and a 20 line edge connector for the read preamp--and 5 small DPDT
>DIP relays to do the switching.   The relay coils occupy a couple of
>lines in the cable connecting the drive to the MCU, so I can shift
>between the heads under software control.
>
>So far, so good.
>
>--Chuck

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Jack Harper, President
Secure Outcomes Inc
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Evergreen, Colorado 80439 USA

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